Dielectric and ferroelectric properties of BNT-based thin films by pulsed laser deposition

We have studied the effect of laser repetition rate on the microstructure, crystallographic orientation, dielectric and ferroelectric properties of pulsed laser deposited 0.94(Bi_0.5Na_0.5)TiO₃-0.04(Bi_0.5K_0.5)TiO₃-0.02BaTiO₃ thin films on SrRuO₃ coated SrTiO₃ substrates. The films were deposited at different repletion rates of 2 Hz, 4 Hz and 8 Hz, while the other processing parameters such as the substrate temperature and oxygen partial pressure were kept constant. It has been demonstrated that the film made at 4 Hz has been epitaxially grown on the substrate with a smooth and flawless surface and shows the best ferroelectric properties among the investigated films. The remnant polarization and dielectric constant for this film were measured to be 13.6 μC.cm^-2 and 425 (at 1 MHz). The leakage current density of the optimized film is 1.3>;10^-5 A.cm^-2 at 320 kV.cm^-1, which is about 3 orders of magnitude lower than those observed in the films prepared at repetition rates of 2 Hz and 8 Hz. The remnant polarizations for the films deposited at 2 Hz and 8 Hz were found to be 8.7 μC.cm^-2 and 7.6 μC.cm^-2, respectively.